微生物与重金属作用机理研究

以微生物与重金属相互作用为对象,结合近年来国内外研究,系统地说明了5种主要分子作用机理,分别为细胞表面吸附、主动运输、细胞内隔绝、胞外沉淀及酶的解毒作用。对重金属产生抗性的基因位于微生物的染色体、质粒和转座子上。最后介绍了多种抗性菌株,并就研究和应用前景进行了分析。     

Fire-resistant performance of a laminated veneer lumber joint with metal plate connectors protected with graphite phenolic sphere sheeting

Creep under fire of laminated veneer lumber (LVL) joined with metal connectors was studied. The fire-resistant performance of LVL butt joints connected with metal plates protected with graphite phenolic sphere (GPS) sheeting was discussed. The GPS sheeting was overlaid on the joint in different sizes and locations. The joint was exposed to a burner with a top flame temperature of 800°C and loaded with a load of 200 N to test for creep under fire. The results showed that the fire-resistant performance of the joint was markedly improved by the sheeting. The size and location of the GPS sheet significantly affected the time to rupture of the specimen, which was six times longer than that without GPS. Temperature measurements at the joint showed that the GPS sheeting distributed the heat along the surface and delayed failure. Thermographic images and analyses clarified the improvement in fire-resistant properties due to GPS.     

上海宝山区城市表土重金属累积的空间分布规律

检测了上海宝山区127个表土样点的重金属含量。宝山区表土Zn、Cr、Cd、Pb、Cu、Ni、Mn的平均含量分别为228.6、127.6、0.56、118.5、55.2、55.7、718.7mg/kg。其中Pb、Zn、Cd的含量分别是上海土壤背景值的5.6、3.0、2.8倍,受污染较明显。宝山区地表的重金属含量呈现出明显的空间分布规律:工业区地表,如吴淞、大场等地,多种重金属污染均很重,Zn、Cr、Cd、Pb、Cu的平均含量分别高达407.6、319.0、0.75、101.2、76.2mg/kg;马路绿地土壤Pb的累积较显著,平均为180.2mg/kg;远郊菜地土壤重金属污染不明显。     

砷镉在不同矿物界面的相互作用过程

重金属元素镉砷由于毒性高、活性大及危害强等特点,其土壤界面化学过程是土壤科学研究中的热点问题。虽然已有大量报道涉及镉砷的界面化学过程研究,但很少排除pH这一重要因子对研究结果的干扰。因此,本研究通过序批式反应,在排除pH干扰的条件下,定量研究了砷及镉在不同矿物界面（包括氧化铝、二氧化钛和高岭石）单独存在以及共同存在条件下的相互作用过程。研究结果表明：不同矿物界面上砷和镉的吸附动力学符合准二级动力学模型,化学吸附为其控速步骤;镉及砷的吸附效率（吸附量/比表面积）在不同矿物界面上均呈现出二氧化钛界面远高于氧化铝界面,而氧化铝界面高于高岭石界面;随着镉/砷浓度比的递增,镉的关键界面作用过程调控机制由静电吸附控制为主逐步转变为静电吸附与形成界面-砷-镉三元络合物共同作用,继而转变为形成表面沉淀控制;而随着砷/镉浓度比的递增,砷的关键界面调控机制发生从吸附控制为主向为沉淀控制为主的转变。该结果可为重金属元素在土壤矿物界面的微观化学作用过程及其调控措施研究提供借鉴。     

稻草秸秆在环境污染治理中的应用研究

稻草秸秆由于其结构的特殊性及廉价易得的特点,被越来越多的研究者利用,用于开发新型高效的吸附剂。综述了稻草秸秆作为吸附剂在环境污染治理中的应用,介绍了对稻草秸秆常用的改性方式,阐述了稻草秸秆吸附剂在重金属离子、有机物等去除方面的研究进展,并展望了稻草秸秆作为环境污染治理吸附剂的发展方向。     

唐山市丰南区沙河口土壤环境质量评价

为了研究唐山市丰南区沙河口土壤环境质量现状,2013年5月开展野外调查和取样分析的工作。采集了土壤和沉积物样37个,主要测试指标包括挥发酚类、氰化物、铬、镍、铜、锌、镉、铅、砷、汞。通过对样品测试数据的分析,发现沙河入海口的大部分土壤质质量为清洁或尚清洁。此外,通过对土壤中各测试指标进行相关性分析,可知重金属铬、镍、铜、锌、镉、铅、砷呈0.01水平显著相关,说明研究区的土壤和沉积物的来源相同。该研究将为进一步开展沙河入海口的生态地质研究工作提供基础参考。     

杨凌城市污泥重金属环境风险评价及合理施用量研究

为科学确定污泥施用量和评价污泥中重金属的环境风险,根据重金属不同形态的环境效应引入毒性响应系数确定了污泥的合理施用量,并采用单项污染指数、内梅罗综合指数和地积累指数对污泥中重金属的污染程度进行了评价.初步确定杨凌城市污泥合理施用量为4.04 t/（hm2·a）,Cd是限制该地区污泥施用的最主要因素,该方法突出了重金属形态的重要性,弥补了以往对重金属只进行总量控制的不足.     

青海省贵南地区一次罕见暴雨天气过程分析

对发生在2012年8月11日18~23时贵南地区的暴雨天气,从环流形势、影响天气系统、物理量场反应等方面进行了分析,结果表明:副高东退和冷空气倒灌是造成大降水的内在机制,同时副高边缘西南暖湿气流发展为大降水提供了充足水汽、能量和动力条件,并在综合分析的基础上,得出其形成原因。     

一种土壤重金属污染源位置的分析方法

对某城市表层土壤中As、Cd、Cr、Cu、Hg、Ni、Pb、Zn等8种重金属元素的含量进行了采样分析,采用域法识别特异值进行数据处理。采用坐标平移法,修正高斯扩散方程,利用MATLAB软件进行拟合,得到了这8种重金属污染源的空间位置坐标。     

Seawater causes rapid trace metal mobilisation in coastal lowland acid sulfate soils: Implications of sea level rise for water quality

Coastal floodplains are highly vulnerable to inundation with saline water and the likelihood of inundation will increase with sea level rise. Sediment samples from floodplains containing coastal lowland acid sulfate soils (CLASS) in eastern Australia were subjected to increasing seawater concentration to examine the probable effects of sea level rise on acidity and metal desorption. Ten soils were mixed with synthetic seawater concentrations varying from 0% to 100% at a solid:solution ratio of 1:10 for 4 h. There was a slight decrease in pH (≈ 0.5 units) with increasing seawater concentration following treatment, yet, calculated acidity increased significantly. In most soil treatments, Al was the dominant component of the calculated acidity pool. Al dominated the exchange complex in the CLASS and, correspondingly, was the major metal ion desorbed. In general, concentrations of soluble and exchangeable Al, Fe²⁺, Ni, Mn and Zn in all soil extracts increased with increasing salinity. Increasing trace metal concentrations with increasing seawater concentration is attributed to the combined effects of exchange processes and acidity. The increasing ionic strength of the seawater treatments displaces trace metals and protons adsorbed on sediments, causing an initial decrease in pH. Hydrolysis of desorbed acidic metal cations can further contribute to acidity and increase mobilisation of trace metals. These findings imply that saline inundation of CLASS environments, even by relatively brackish water may cause rapid, shorter-term water quality changes and a pulse release of acidity due to desorption of acidic metal cations.